Thanks for asking!
And the answer is very simple: at the same resolution, the performance will be exactly identical between the UGA-2K-A (which has a DislpayLink 195 chip in it) and the UGA-165 (which has a DisplayLink 165).
Now in contrast, the UGA-125 (which has a DisplayLink 125 chip) will have performance differences, as it has just a single decode engine (a single USB enpoint that rendering happens on).
With more details at http://displaylink.com/displaylink_ha…
Outside of which DisplayLink chip and driver version used, it’s actually hard for an adapter to have any significant effect on performance any direction.
As a user, the biggest effect you can have on performance is running at the lowest resolution that still looks great on your monitor (or, similarly, pick a monitor that’s physically large with less pixel resolution). Fewer pixels will mean less demand on the 480Mbps USB 2.0 bus.
So sometimes the UGA-125 actually has higher perceived performance, just because it has a lower max mode, and therefore has less pixels it has to compress with the CPU and move over USB.
Again, thanks for the question! Hope that explains the differences.